Archaeologists have investigated hundreds of ditched enclosures - similar to those constructed in Europe in Neolithic times - that were constructed in the western Brazilian Amazon some 2000 years ago. More than 450 of the mysterious structures have been revealed as a result of deforestation of the area, with the earthworks previously being hidden from view by trees.
The function of the geoglyphs remains unknown, though excavations have revealed very few artefacts, suggesting they were not the site of permanent settlements, but rather more likely were used sporadically as ritual gathering places.
The archaeologist who excavated some of the sites, Dr Jennifer Watling, compared the Amazon geoglyphs with European henges:
It is likely that the geoglyphs were used for similar functions to the Neolithic causewayed enclosures, i.e. public gathering, ritual sites.
It is interesting to note that the format of the geoglyphs, with an outer ditch and inner wall enclosure, are what classicly describe henge sites. The earliest phases at Stonhenge consisted of a similarly layed-out enclosure.
The research team found that the inhabitants of the area cleared the forest in small areas in order to build the geoglyphs, with the trees then growing back and hiding them from view until now. That finding, Dr Watling noted, "really challenges the idea that Amazonian forests are ‘pristine ecosystems'".
However, she was quick to note that fact should not be used as an excuse for modern deforestation:
Our evidence that Amazonian forests have been managed by indigenous peoples long before European contact should not be cited as justification for the destructive, unsustainable land-use practiced today.
It should instead serve to highlight the ingenuity of past subsistence regimes that did not lead to forest degradation, and the importance of indigenous knowledge for finding more sustainable land-use alternatives.
The research will be published in PNAS soon under the title "Impact of pre-Columbian “geoglyph” builders on Amazonian forests".